Inter-rater Reliability of Sustained Aberrant Movement Patterns as a Clinical Assessment of Muscular Fatigue

Frank Aerts1, 3, Kathy Carrier1, 2, Becky Alwood*, 3
1 Department of Physical Therapy, Andrews University, Berrien Springs, MI, USA
2 Physical Therapy Services of West Michigan, Kalamazoo, MI, USA
3 Department of Wellness & Rehabilitation, Indiana University Health La Porte Hospital, La Porte, IN, USA

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© Aerts et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (, which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Wellness & Rehabilitation, Indiana University Health La Porte Hospital, La Porte, IN, USA; E-mails:;



The assessment of clinical manifestation of muscle fatigue is an effective procedure in establishing therapeutic exercise dose. Few studies have evaluated physical therapist reliability in establishing muscle fatigue through detection of changes in quality of movement patterns in a live setting.


The purpose of this study is to evaluate the inter-rater reliability of physical therapists’ ability to detect altered movement patterns due to muscle fatigue.


A reliability study in a live setting with multiple raters.


Forty-four healthy individuals (ages 19-35) were evaluated by six physical therapists in a live setting.


Participants were evaluated by physical therapists for altered movement patterns during resisted shoulder rotation. Each participant completed a total of four tests: right shoulder internal rotation, right shoulder external rotation, left shoulder internal rotation and left shoulder external rotation.


For all tests combined, the inter-rater reliability for a single rater scoring ICC (2,1) was .65 (95%, .60, .71) This corresponds to moderate inter-rater reliability between physical therapists.


The results of this study apply only to healthy participants and therefore cannot be generalized to a symptomatic population.


Moderate inter-rater reliability was found between physical therapists in establishing muscle fatigue through the observation of sustained altered movement patterns during dynamic resistive shoulder internal and external rotation.

Keywords: Dose, medical exercise therapy, muscle fatigue, physical therapy, shoulder, therapeutic exercise.